An international interdisciplinary workshop is bieng organized on subviral pathogens, viroids and prions, to further the concept of so far unrecognized human and animal types of subviral pathogens. Viroids have appeared on the scene first and are now universally recognized. The true nature of the agents of subacute spongiform encephalopathies, on the other hand, is still enigmatic. The scrapie agent is radically different from either viruses or viroids, consisting of a hydrophobic protein. This revolutionary new concept with far-reaching implications not only for virology but even more for human and veterinary medicine, as well as for basic molecular biology, will be the subject of the interdisciplinary workshop. The contributors, recognized authorities in their specialized fields, were chosen on the basis of their outstanding knowledge of the subjects. Viroids are included because they serve as a convenient model of one type subviral agent, the nature of which has been elucidated. Work on the control of plant viroid diseases is in progress and it might be relevant for similar work to control spongiform encephalopathies, Creutzfeld-Jacob and possibly Alzheimer's disease. The workshop will be of importance because the newly emerging concepts of subviral pathogens will be discussed and the published information made available to an international audience of the first time.